Bridges typically comprise a plurality of discrete structural members supported on pillars and disposed end to end with an expansion gap between adjacent members to provide the bridge deck surface or roadway.
Cracking and deterioration of the roadway and structural members is a common problem at bridge joint regions. Vehicular impact above the expansion or contraction due to changes in weather conditions, contribute to this cracking and deterioration. Also, cracks and potholes are formed in the roadway that are hazardous to drivers and lead to further deterioration of the supporting bridge structure. This and other problems with bridge joints are more fully set forth in U.S. Pat. No. 5,024,554 to Benneyworth et al.
Previous attempts to overcome the well-known problems associated with bridge joints have achieved limited success. The methods for sealing bridge joints proposed in both U.S. Pat. No. 4,324,504 to Cottingham and U.S. Pat. No. 5,024,554 to Benneyworth et al. require the application of a hot binder to aggregate in the channel. Further, the healed binder would not bond properly if installed on a cold day or under wet weather conditions. Moreover, even if the binder material was properly heated and installed during optimal weather conditions, the elasticity of the resulting bridge joint was generally limited to less than two inches of movement for a bridge joint twenty inches wide.
The polysulfide elastomer binder employed in the present invention has not to Applicant's knowledge been previously used to construct bridge joints. Rather, it has been used to fill cracks or joints between slabs in the roadway. Consequently, the combination of a polysulfide elastomer binder and aggregate chips to transfer vehicular stress and to withstand movement of adjacent support members is believed to be novel.
Moreover, the design considerations are significantly different for constructing bridge joints as opposed to filling other joints or cracks in the roadway. For example, these other joints are much more narrow and often more shallow than bridge joints and thus are not required to withstand the same magnitude of vehicular impact stress. Further, the structural members of a bridge are directly exposed to dynamic changes in weather conditions, but structural members beneath a roadway are typically insulated by the ground. Consequently, bridge joints are frequently subject to more extreme contraction and expansion from weather conditions than are other joints. As a result of these unique design considerations and to the best of Applicant's knowledge, the polysulfide elastomer binder has not been combined with aggregate when used to fill these other joints. Therefore, the qualities of the polysulfide elastomer binder, when used in combination with aggregate to fill a bridge joint, were heretofore unknown.